Fan



April .21, 1936. F. CHARAVAY' FAN Filed Nov. 17, 1933 WMZ a024,

ATTORNEY Patented Apr. 21, 19 36 UNITED STATES nurses PATEN OFFICE.

aos'mso Frederick Charavay, Piqua, Ohio, assignor of onehalf to Hartzell Industries, Inc., Pique, Ohio, a corporation oi Delaware Application November 1'1, 1933, Serial No. 698,528

6 Claims.

a large flow of air .or other fluid in a-practically noiseless manner.

Another object of the invention is the provision of a fan having blades of such form as to efficiently create a comparatively high pressure differential between the fan inlet and outlet.

Another object of the-invention is the pro vision of a fan having blades so arranged as to provide a substantially radial flow of air or other fluid, the distance between adjacent blades increasing outwardly toward the blade tips and increasing inwardly towards the inner ends of the blades whereby turbulence of the fluid is minimized.

Another object of the invention is the provision tion will be apparent from the following description, the appended claims and the accompanying drawing, in which Fig. 1 is a side elevation of a fan rotor embodying the present invention;

Fig. 2 is an enlarged fragmentary view corresponding to Fig. 1;

Fig. 3 shows one form of fan arrangement in a ventilating system or the like; and

Fig. 4 shows a second arrangement for the fan rotor and driving means. I

Referring more particularly to the drawing by reference numerals, i designatesgenerally the rotor of a fan or blower adapted to move or propel air or other gaseous medium and suitable for utilization in many ways for ventilation or other purposes. The rotor comprises a body member or disk ll having a supporting hub I? by means of which it may be attached to a driving shaft, the projecting end of the hub being preferably split radially soth'at the driving shaft may be held securely by means of the clamping bolts i3. On the outer portion of the disk ii centrifugal and aerofoil action.

blades M are preferably provided as an integral casting of suitable metal.

In the form of construction illustrated in Fig. 3,

' the fan rotor Iii is secured to a shaft l6 constituting an extension of the shaft of an electric motor ii. The motor is supported by means of suitable straps l8 and is which are fastened to a fixed mounting plate 20 so that the rotor operates-with a. very small clearance spacing from the .plate, the imperforate disk ii of the 10" rotor preventing the discharge of airin an axial direction and causing air to be circulated from the chamber 22 on the motor side of the plate 26 and through the opening 23 provided in the plate 20, the air then flowing in radial directions past the blades It as they revolve. The mounting plate may form the wall of a room or other chamber or may be adapted to be secured in an opening in a room or chamber to be ventilated.

In the form of construction shown in Fig. 4, .20 the rotor. corresponding in form to the rotor I0 is fixed to the shaft of an electric motor 28. which is supported by means of straps 21 from the fixed mounting plate 28, the motor in this case being arranged on the side of the mounting 25 plate to which the air flows. The mounting plate 28 may be secured in any suitable manner to the end of a duct or pipe 29 for withdrawing hot air or the like; Thus the air flows from the pipe 29 out past the blades on the rotor, the air flowing 30 past the blades being dissipated in a generally radial outward direction and not coming in direct contact with the motor. The rotor Ill is adapted for rotation in the direction of the arrows'shown in Figs. 1 and 2. The Q diameter of the rotor may be about 10" in which case a speed of about 1780 R. P. M. is quite satisfactory for eflicient operation. l-Iowever, the rotor may be made very much larger or smaller and a suitable speed of operation selected in ac- 40 cordance with the particular conditions of operation. As will be noted from the drawing, the blades'are quite thick between their outer and inner ends and are adapted to efilciently force the air or other fluid in a generally outward direction, drawing air substantially axially and forcing it outwardly by reason of a combined 7 The forward side of each blade, starting with the inner blade tip 30 extends in a generally radial direction for a substantial distance and then curves gradually rearwardly with respect to the direction of rotation so that the outer blade tip ti on the forward side thereof projects almost tangential ly. The forward face of the outer end oi the blade as indicated at 32 departs very gradually from a tangential direction, this portion being arranged preferably at an angle of two or three degrees from a true tangent so that this portion of the blade, in acting on the air transferred to it, will gradually change the direction of the air so that it leaves the tip of the blade with .comparatively small forward propelling force applied at that particular point. The streams of air flowing outwardly between the various blades are therefore so urged as to flow substantially radially as they leave ,the blades. Moreover the fluid leaving the surface 32 of one blade merges with the flow passing "between that blade and the next succeeding blade without creating a turbulent condition. This lack of turbulence and gradual change in direction of air flow in such manner as to cause a continuous radial flow produces a quiet operation at high efliciency, and creates a comparatively large pressure differential between the inlet and outlet sides of the fan.

The rear side of the blade as indicated by the numeral 34 is preferably curved in a concave manner, although the curvature of the rear side is very much less than the degree of curvature of the forward side of the blade. The blade, at the middle portion, is about one-half as thick as the total blade length measured in a radial direction. Moreover it will be noted that with the arrangement of blades as herein set forth, the annular distance between adjacent blades increases both inwardly and outwardly from a point of minimum spacing at, this point of minimum spacing being located not substantially inwardly of the median circle 35 of the blade series, the median circle being defined as the circle half-way between the circle containing the outer tips and the circle containing the inner tips of the blades. The point of minimum spacing a: is preferably much closer to the outer blade tips than it is to the inner blade tips, thus providing a channel 36 between adjacent blades which increases in width inwardly toward the inner blade tips and in which the air tends to be compressed by the centrifugal action due to the high speed of rotation. The compression eifect-of the air takes place without the creation of any substantial turbulence due to the gradual change in cross sectional area of the channel provided between adjacent blades. When the air reaches the point of minimum spacing it tends to expand but does so in a very gradual manner as it travels outwardly toward the blade tips. The channel outwardly of the point of minimum spacing, as

will be apparent, increases gradually in an outward direction and more and more rapidly out toward the blade tips 3| so that as the more rapidly moving parts of the impeller more re- -mote from the axis of rotation act on the air blade ends opposite their point of attachment to the rotor disk, although it is preferred that the blades be made hollow, each being attached to the disk H at one end of the blade, preferably in an integral manner, the opposite ends of the blades being preferably unsupported and open at their ends so that a chamber or space 38,

' closed on all sides but one, is within each blade.

Thus when, the various blades operate at high speed close to a supporting plate 20, the space between the plate and blades will be more effectively sealed against pressure losses, the dead air within the blade chambers acting to hinder direct passage of air between the blades and the fixed plate 20.

The arrangement of blades as herein set forth is particularly desirable for fans or blowers adapted to operate quietly} under substantial pressure differential, as it is possible to providea difference in pressure on opposite sides of the fan several times as large as is obtainable in blades of the ordinary airplane propeller type for example, in which there is a considerable loss in pressure by reason of return flow through the central portions close to the hub.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A fan rotor of the character described comprising a rotatable body member, and an annular series of blades on said member adapted to create a radially outward flow when the body member is rotated, each blade having an outer tip portion decreasing in cross section outwardly from the axis of rotation and extending rearwardly with respect to direction of rotation, the forward side of the blade at the tip extending approximately tangentially, and having an inner portion decreasing in cross section inwardly toward the axis of rotation and terminating at a distance from the axis of rotation, the forward side of the inner portion of the blade extending substantially radially and merging gradually into the forward tip portion.

2. In a fan,a rotatable annular series of similar blades adapted to create a radially outward flow, each blade having a substantial'thickness, the outer tip of the blade extending rearwardly with respect to the direction of rotation and tapering substantially to a point with its forward side extending in a substantially tangential direction, the annular distance between adjacent blades increasing both radially inwardly and radially outwardly from a point of minimum spacing, the forward tip portion of the blade merging gradually into an inner inwardly extending forward portion.

3. In a fan, a rotatable annular series of similar blades adapted to cause an outward flow, each blade having a substantial thickness, the outer tip of the blade tapering substantially to an edge and extending rearwardly with respect to the direction of rotation in a substantially tangential direction, the forward tip portion of the blade merging gradually into an inner inwardly extending forward portion, the annular distance between adjacent blades increasing both radially inwardly and radially outwardly from apoint of minimum spacing, which point is substantially closer to the outer blade tip than to the inner blade tip, and the annularspacing increasing outwardly most rapidly adjacent the outer periphery of the fan.

4. A fan rotor of the character described adapted to cause an outward flow comprising a rotatable body member, an annular series of similar blades on said body member, each blade having an outer tip portion decreasing outwardly in cross-section and extending rearwardly with respect to the direction of rotation, said blades each having a 5. A fan rotor of the character (1 cribed adapted to cause an outward flow comprsing a rotatableone-piece member forming a disk and an annular series of hollow blades on one side of said disk at the peripheral portions thereof, said blades having spaced front and rear sides and being open at the end remote from said disk, and in combination therewith, a fixed plate spaced slightly from the open ends of all said blades.

6. A fan rotor of the character described comprising a one-piece member forming a disk and an annular series of similar hollow blades on'one side of said disk at the peripheral portions thereof, said bladeshaving spaced front and rear sides and being open at the end remote from said disk, the distance between adjacent blades increasing both inwardly and outwardly to the inner and outer ends of the blades respectively from a point of minimum spacing, and in combination therewith, a fixed plate spaced slightly from the open ends of all said blades.

FREDERICK CHARAVAY. 

